Naturally occurring soils retain moisture under a range of climatic conditions, including dry conditions. The ability to retain moisture is an important factor in a soil's ability to support plants and other organisms present in a given ecosystem. A soil's ability to retain moisture is influenced by many factors, including its texture, structure, and the presence of active populations of soil microbes.
Soil moisture is an important factor influencing microbial respiration, and in turn, microbial processes modulate water availability in soil through production of extracellular polymeric substances (EPS). EPS is a hydrogel composed of deoxyribonucleic acid (DNA), protein, and polysaccharides that is naturally produced and secreted by many types of bacteria to form biofilms. EPS protects bacteria from predation, moderates nutrient availability, retains moisture in the colony, and promotes an aggregated soil structure.
Global climate change is predicted to amplify extreme events in a hydrological cycle, including powerful storms and prolonged droughts. Such extreme events can lead to widespread reduction in soil moisture, having implications for sustainable food, feed, and fiber production. One of the major factors limiting primary productivity in terrestrial ecosystems will be sub-optimal soil moisture.
A better understanding of the interaction between physical soil structure and biological processes is useful to predict the moderating effects of soil bacteria on retaining soil moisture, and may enable agriculture biotechnology that enhances natural soil processes for improved resiliency of terrestrial ecosystems.